Fatigue during assembly is a crucial factor in quality assurance. SISO is ergonomically applied only from the side or above. A SISO user doesn't want to be kneeling and constantly getting up. Many users and designers are impressed by its simplicity every day. Similarly, the installer wants a free hand for adjustments and visual confirmation of tightness. Once the screw is in, it holds. SISO is simple – screw it in – done!